The long-term goal of these studies is to understand the molecular basis of assembly of specific tissue and organ structures by testing the hypothesis that tissue dependent expression of transcript and protein variants determines the specific micro-architecture of the extracellular matrix in different tissues. To reach this goals, we will use a combination of DNA cloning, immunohistochemistry, and transgenic mice technology to analyze the differential expression and interaction properties of the FACIT components IX, XII, and XIV. We will also study the regulated expression and biological role of a novel collagen (type XVII) with multiple triple-helical domains and sequence characteristics typical of proteoglycans. We believe our studies will contribute significantly to the molecular understanding of tissue-dependent diversity of extracellular matrices. This information is essential for understanding normal tissue and organ morphogenesis as well as connective tissue disease processes and genetic abnormalities.